> At this point, we can say
>
> quadratic c z = addCx (mulCx z z) c
>
> This is, of course, awful.

I missed a step. I meant to use this as a neat opportunity to point out 
that you can do

   quadratic c z = (z `mulCx` z) `addCx` c

Putting any function name in backticks magically makes it infix. This is 
an improvement, although not a large one in the example given.

Then again, for standard arithmetic operations, there are well-known 
symbols, which are much more concise. For less common operations like 
set union, writing

   setA `union` setB

is regarded by many as being nicer than

   union setA setB

Each to their own. Perhaps the "mod" function is a better example:

   p^e `mod` m

verses

   mod (p^e) m

Weirdly, you can even set an "operator precedence" for backtick infix...

(In case I didn't explain, "infixr" means infix with Right 
associativity, while "infixl" means Left associativity.)

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